1. Technical Field
The disclosure relates to a technique to control a temperature of a heated body that is heated by a heater to a target temperature.
2. Description of the Related Art
A situation, which an electronic component is heated to a constant temperature by a heater to stabilize the characteristics of the electronic component, is existed. As an example, what is called an oven crystal controlled oscillator (OCXO) is illustrated. Since a crystal unit changes its frequency in response to the temperature, this type of crystal controlled oscillator is used when an output frequency with high stability is required.
The OCXO detects temperature in the atmosphere using a temperature detector disposed near the crystal unit, adjusts a temperature of a heater in according to the temperature in the atmosphere, and controls the temperature in the atmosphere of frequency oscillation unit. Thus, after the OCXO is started up, the temperature in the atmosphere of frequency oscillation unit is gradually brought close to a setting value while the temperature repeats overshooting to a higher temperature side than the setting value and undershooting to a lower temperature side than the setting value. The maximum value of a start-up current that flows through the OCXO at that time and the time required for stabilization of the frequency are determined by an arrangement layout and a specification of hardware such as transistors and resistors that constitute the OCXO circuit. However, since the start-up time and the start-up current required by a customer depend on an intended use, an oscillator has to be adjusted by rearranging a hardware constitution according to a customer requirement.
Japanese Unexamined Patent Application Publication No. 2001-75605 discloses a technique using feedback control to reduce the overshooting and the undershooting of the start-up current. However, the magnitude of the start-up current and the time required for starting up are not made variable.